Spacecraft capture mechanism

ABSTRACT

The present invention provides a capture mechanism for capturing and locking onto the Marman flange located on the exterior surfaces of spacecraft/satellites. The capture mechanism achieves its goal of quickly capturing a target spacecraft by splitting the two basic actions involved into two separate mechanisms. One mechanism performs the quick grasp of the target while the other mechanism rigidizes that grasp to ensure that the target is held as firmly as desired. The jaws can be set up to grasp gently, firmly, or even not close completely on the target. Once the jaws have sprung shut, a second mechanism draws the jaws (and their closing mechanism) back into the body of the tool pulling the captured target onto two rigidization surfaces. The mechanism keeps pulling backwards until a pre-established preload is reached at which point the target is considered suitably rigidized to the capture mechanism.

FIELD OF THE INVENTION

The present invention relates to mechanisms for capturing spacecraft,and more particularly the present invention relates to a capture devicefor capturing and rigidising a bracket mounted on a spacecraft.

BACKGROUND OF THE INVENTION

Grappling free flying target objects in space involves systems whichpossess the following capabilities: acquiring the relative location ofthe target object's position is relative to the capture mechanism,establishing and tracking the relative motion of the target and capturemechanism, effecting a timely reduction in the relative separationbetween the two objects and then acting to capture the target objectfast enough that it is grasped by the capture mechanism before thetarget moves out of the way on its own or is knocked away by the capturemechanism (an event known as “tip off”). The methods by which therelative positions and motions of the capture mechanism and the targetobject are established and tracked and the methods by which the capturemechanism is moved into position to capture are not part of thisdescription. In general these may be accomplished through the orbitaland attitude control of the capture spacecraft and in some casesaugmented with manipulator arms which provide further dexterity andspeed in the final stage of approach and positioning of the capturedevice with respect to the spacecraft which is to be captured, all thesetechniques are well known to those skilled in the art.

Capture mechanisms do however play a part in how large the relativemovement can be between the target object and the capture mechanism. Thefaster the capture mechanism can perform an initial capture, the greaterthe relative motion can be between the two objects. This is because ifthe mechanism acts quickly enough, the target will have less time tomove out of the way. For a given mechanism, the faster it works, thefaster the relative motions can be between target object and capturemechanism. Providing a capture mechanism that permits a greater relativemotion between the capture mechanism and the target object hassignificant benefits to both objects.

SUMMARY OF THE INVENTION

The capture mechanism disclosed herein is designed with a view tocapturing several of the standard spacecraft Marman clamp flangeinterfaces (see attached interface documents for specific variations).The vast majority of satellites launched for Western customers, bothcommercial and military, use this interface due to its heritage andreliability. That said, the capture mechanism disclosed herein can beused to quickly capture other target spacecraft protrusions, the keycriteria being the ability of the mechanism jaws to close on theprotrusion from both sides and that, when closed, at least one side ofthe target protrusion has an extended profile that at least one of thetwo jaws can get behind with which to contain the target. Examples ofpotentially suitable target profiles would include, but not be limitedto, personnel handles and grab rails, I-beams and C-channels,T-fittings, pipes, structural members, etc.

The capture mechanism achieves its goal of quickly capturing a targetspacecraft by splitting the two basic actions involved into two separatemechanisms. One mechanism performs the quick grasp of the target whilethe other mechanism rigidises that grasp to ensure that the target isheld as firmly as desired. To achieve a speedy grasp, the graspingaction is powered by springs and an over-centre mechanism triggeredeither mechanically by a plunger or electronically by sensors and asolenoid. This forces two sets of jaws, one on either side of the objectto be grasped, to close quickly over the target object. The jaws can beset up to grasp gently, firmly, or even not close completely on thetarget. The key is that they must close tightly enough so that theprotrusions on the target cannot escape from the jaws due to anypossible motions of the target. Once the jaws have sprung shut, a secondmechanism draws the jaws (and their closing mechanism) back into thebody of the tool pulling the captured target onto two rigidisationsurfaces. The mechanism keeps pulling backwards until a pre-establishedpreload is reached at which point the target is considered suitablyrigidised to the capture mechanism.

Another embodiment includes a system for capturing a rail and or flangefeature on a free flying spacecraft, comprising

a) a capture mechanism including a two stage grasping tool including

-   -   i) a quick grasp mechanism mounted for movement in a housing,        said quick grasp mechanism configured to clamp said feature when        said feature is in close proximity to, and triggers, said quick        gasp mechanism to soft capture the feature;    -   ii) a rigidizing mechanism configured to draw the quick grasp        mechanism and soft captured feature into said housing till said        feature abuts against a rigidisation surface located in said        housing to rigidize the feature and spacecraft against said        housing.

In this aspect the system may include

a) a positioning device attached to the capture mechanism capable ofpositioning the capture mechanism into close proximity to the feature totrigger the quick grasp mechanism; and

b) a sensing system for ascertaining a relative position of the capturemechanism and the feature.

In addition, the system may include a computer control system connectedto said sensing system and programmed to position the capture mechanismin close proximity to said feature to trigger said quick graspmechanism.

An embodiment of a capture mechanism disclosed herein includes

a) a first housing section, a quick grasp mechanism mounted in saidfirst housing section, said quick grasp mechanism including

-   -   clamping jaws having proximal sections pivotally mounted to a        front portion of said first housing section and extending        outwardly from a front of said first housing section,    -   a biasing mechanism located in said first housing section        configured for biasing distal sections of the clamping jaws        apart, the biasing mechanism including an elongate plunger        mounted for reciprocal movement along an axis of the first        housing section, the biasing mechanism including a cam mechanism        pivotally mounted to said elongate plunger and configured to        have a cam portion engage said clamping jaws to bias the distal        sections of the clamping jaws apart when the elongate plunger is        fully extended forward of the first housing section, the cam        mechanism being configured so that when the elongate plunger        contacts a bracket mounted to a spacecraft and is moved inwardly        into said first housing section the cam mechanism pivots with        respect to said elongate plunger causing the cam portions        engaging said clamping jaws to move forward forcing the distal        ends of the clamping jaws to pivot toward each other thereby        capturing a portion of the bracket; and

b) a second housing section mounted to a back of said first housingsection, a rigidisation mechanism mounted in said second housingsection, said rigidisation mechanism including

-   -   a pulling mechanism connected to the elongate plunger configured        to draw the elongate plunger and the clamping jaws further into        the first housing section, the first housing section and cam        mechanism being configured so that as the clamping jaws are        withdrawn into the first housing section the cam portions        engaging said clamping jaws are biased closer together, the        pulling mechanism being configured to further pull the clamping        mechanism into said first housing until a portion of the bracket        abuts up against a rigidisation bracket to thereby rigidiize the        captured spacecraft to the capture mechanism.

Another embodiment of a capture mechanism for capturing a bracketmounted to a spacecraft, comprises:

a) a first housing section, a quick grasp mechanism mounted in saidfirst housing section, said quick grasp mechanism including

-   -   clamping jaws having proximal sections pivotally mounted to a        front portion of said first housing section and extending        outwardly from a front of said first housing section,    -   a biasing mechanism located in said first housing section        configured for biasing distal sections of the clamping jaws        apart, the biasing mechanism including an elongate plunger        mounted for reciprocal movement along an axis of the first        housing section, the biasing mechanism including a cam mechanism        pivotally mounted to said elongate plunger and configured to        have a cam portion engage said clamping jaws to bias the distal        sections of the clamping jaws apart when the elongate plunger is        fully extended forward of the first housing section, the cam        mechanism being configured so that when the elongate plunger        contacts a bracket mounted to a spacecraft and is moved inwardly        into said first housing section the cam mechanism pivots with        respect to said elongate plunger causing the cam portions        engaging said clamping jaws to move forward forcing the distal        ends of the clamping jaws to pivot toward each other thereby        capturing a portion of the bracket; and

b) a second housing section mounted to a back of said first housingsection, a rigidisation mechanism mounted in said second housingsection, said rigidisation mechanism including

-   -   a pulling mechanism connected to the elongate plunger configured        to draw the elongate plunger and the clamping jaws further into        the first housing section, the first housing section and cam        mechanism being configured so that as the clamping jaws are        withdrawn into the first housing section the cam portions        engaging said clamping jaws are biased closer together, the        pulling mechanism being configured to further pull the clamping        mechanism into said first housing until a portion of the bracket        abuts up against a rigidisation bracket to thereby rigidiize the        captured spacecraft to the capture mechanism; and

c) a third housing, said first and second housings being reciprocallymovable along a longitudinal axis of said third housing, said thirdhousing including

-   -   i) an extension mechanism for extending said first and second        housing out of said third housing a predetermined distance,    -   ii) a retraction mechanism for drawing said first and second        housings back into said third housing, and    -   iii) a locking mechanism for locking said first and second        housings within said third housing.

A further understanding of the functional and advantageous aspects ofthe disclosure can be realized by reference to the following detaileddescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, withreference to the drawings, in which:

FIG. 1A shows a perspective view of the capture mechanism of the presentinvention in the open position and approaching a flange located on aspacecraft;

FIG. 1B is a side view of the capture mechanism of FIG. 1A in the openposition;

FIG. 2 shows a perspective view of the capture mechanism of FIG. 1 butfrom a different perspective than shown in FIG. 1;

FIG. 3 is a perspective view similar to FIG. 1 but with the beinggrasped by the capture mechanism which is in the closed position;

FIG. 4 is a top view of the capture mechanism taken along arrow 4 ofFIG. 3;

FIG. 5 is a partial cross sectional of the capture mechanism in the openposition taken along line 5-5 of FIG. 1A;

FIG. 6 is a partial cross sectional of the capture mechanism in theclosed position taken along line 6-6 of FIG. 3;

FIG. 7 is an expanded view of the cross section of FIG. 6 showing theclamping jaw portion with the clamping jaws in the closed position andshowing details of the retraction mechanism;

FIG. 8 is an expanded view of the cross section of FIG. 5 of theclamping jaw portion with the clamping jaws in the open position;

FIG. 9 is a perspective view of the capture mechanism shown in crosssection in FIG. 8 with the jaws in the open position and absent a camdrive link so that the cam drive springs can be seen;

FIG. 10 is a partial cross sectional diagram taken along the line 10-10of FIG. 8;

FIG. 11 is a full cross sectional diagram taken along line 10-10 of FIG.8 d;

FIG. 12 is a cross sectional view of an alternative embodiment of acapture mechanism in the loaded position with the clamping jaws open andready to grasp a Marmanm flange;

FIG. 13 is a cross sectional view of the capture mechanism of FIG. 11 inthe sprung position with the clamping jaws gripping and closed on aMarman flange;

FIG. 14 is a cross sectional view of the capture mechanism of FIG. 11 inthe retracted and locked position with the clamping jaws gripping andclosed on a Marman flange; and

FIG. 15 is a block diagram showing a servicing satellite equipped withthe present capture mechanism for capturing a satellite; and

FIG. 16 shows a non-limiting exemplary example of a computer controlsystem that may be used to control the actions of the robotic tool.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments and aspects of the disclosure will be described withreference to details discussed below. The following description anddrawings are illustrative of the disclosure and are not to be construedas limiting the disclosure. The drawings are not necessarily to scale.Numerous specific details are described to provide a thoroughunderstanding of various embodiments of the present disclosure. However,in certain instances, well-known or conventional details are notdescribed in order to provide a concise discussion of embodiments of thepresent disclosure.

As used herein, the terms, “comprises” and “comprising” are to beconstrued as being inclusive and open ended, and not exclusive.Specifically, when used in this specification including claims, theterms, “comprises” and “comprising” and variations thereof mean thespecified features, steps or components are included. These terms arenot to be interpreted to exclude the presence of other features, stepsor components.

As used herein, the term “exemplary” means “serving as an example,instance, or illustration,” and should not be construed as preferred oradvantageous over other configurations disclosed herein.

As used herein, the terms “about” and “approximately”, when used inconjunction with ranges of dimensions of particles, compositions ofmixtures or other physical properties or characteristics, are meant tocover slight variations that may exist in the upper and lower limits ofthe ranges of dimensions so as to not exclude embodiments where onaverage most of the dimensions are satisfied but where statisticallydimensions may exist outside this region. It is not the intention toexclude embodiments such as these from the present disclosure.

The capture device disclosed herein has been conceived to address twotypes of spacecraft/space object capture. In general, it is forcapturing “non-prepared” objects. This refers to a class of clientspacecraft which were not designed with purpose made features that wouldbe used for later capture by a servicing spacecraft once the clientspacecraft was in orbit. The capture device has been designed to capturethrough a grasping action natural features like launch adapter ringswhich are present on most spacecraft for the purposes of attachment tothe launch vehicle prior to release on-orbit. Other natural featuressuch as rails would also be applicable. A secondary feature of thesenon-prepared spacecraft for which this proposed capture device isintended is non-cooperative spacecraft. These are client spacecraftwhich are no longer under standard attitude control with the spacecraftno longer held in a stable attitude, but are instead are tumbling, i.e.rotating in one or more axis with respect to their desired pointingdirection. In non-tumbling capture, the rendezvousing servicerspacecraft generally is moving relative to the client on a single axisof motion. In capturing a tumbling spacecraft, the servicer spacecraftand/or its manipulator arm must close the separation between it and theclient in a number of axes. This puts a premium on the capture devicebeing able to quickly grasp the tumbling spacecraft in what is a muchnarrower capture zone time, generally limited by the responsiveness ofthe spacecraft attitude and orbital control system and theresponsiveness and peak rates of the manipulator arm.

The pool of viable targets will increase with the capture mechanismmechanism's ability to more quickly capture a mechanical feature on theclient over a larger range of relative motion. In addition, thespacecraft carrying the capture mechanism will not have to control itsown position as precisely, which will result in less propellant beingneeded and less precise avionics needing to be developed resulting inlower overall mission costs.

This premium on quickly grasping the client which is potentiallytumbling presents a challenge for typical robotic grippers. They mustquickly close, yet produce a sufficiently high applied gripping load toensure that the captured spacecraft remains grasped as forces/momentsdevelop at that interface as the servicer spacecraft and manipulatorarrests the relative motion of the client. This presents a challenge fortypical single action gripping devices which generally use some sort ofgearing or transmission in the clamping action. In space systems, thisgearing is needed because there is a need for lightweight actuators. Asthe gearing is increased to compensate for the low torque of theactuator, the penalty is a lower closure rate. This design trade-off insingle action robotic grippers is a primary motivation for the twostage, capture device disclosed.

Broadly speaking, the capture mechanism disclosed herein achieves itsgoal of quickly capturing a target spacecraft by splitting the two basicactions involved into two separate mechanisms. One mechanism performsthe quick grasp of the target while the second mechanism rigidises thatgrasp to ensure that the target is held as firmly as desired. To achievea speedy grasp, the grasping action is powered by springs and anover-centre mechanism triggered either mechanically by a plunger orelectronically by sensors and a solenoid. This forces two sets of jaws,one on either side of the object to be grasped, to close quickly overthe target object. The jaws can be configured to grasp gently, firmly,or even not close completely on the target. However it is preferred thatthey close tightly enough so that the protrusions on the target cannotescape from the jaws due to any possible motions of the target. Once thejaws have sprung shut, a second mechanism draws the jaws (and theirclosing mechanism) back into the body of the tool thereby pulling thecaptured target onto two rigidisation surfaces. The mechanism keepspulling backwards until a pre-established preload is reached at whichpoint the target is considered suitably rigidised to the capturemechanism.

PARTS LIST

This embodiment of the capture mechanism tool is comprised of thefollowing parts:

-   1. capture mechanism housing-   2. rigidisation mechanism housing-   3. rigidisation mechanism mount-   4. trigger plunger-   5. single jaw-   6. double jaw-   7. rigidisation bracket (quantity of 2)-   8. motor bracket (quantity of 2)-   9. motor-   10. gearbox-   11. collet-   12. rigidisation drive shaft-   13. rigidisation drive nut-   14. rigidisation drive nut spacer-   15. rigidisation drive spacer retaining ring-   16. mechanism mount-   17. mechanism mount fastener-   18. capture mechanism stop pin (quantity of 2)-   19. capture mechanism return pin (quantity of 2)-   20. capture mechanism return spring (quantity of 2)-   21. capture mechanism cam (quantity of 2)-   22. cam drive link (quantity of 2)-   23. plunger drive pin-   24. cam drive link pivot pin (quantity of 2)-   25. cam drive spring support pin (quantity of 2)-   26. cam drive pin (quantity of 2)-   27. plunger draw bar-   28. plunger draw bar bolt (quantity of 2)-   29. plunger draw bar nut (quantity of 2)-   30. rigidisation preload bushing-   31. rigidisation preload spring-   32. rigidisation preload washer-   33. rigidisation preload spring screw-   34. capture mechanism frame (quantity of 2)-   35. cam drive spring access plate (quantity of 2)-   36. cam drive spring (quantity of 2)-   37. jaw hinge pin (quantity of 2)-   38. plunger reset stop ring-   39. target Marman flange-   40. target spacecraft

The structure of the capture mechanism will first be described andparticular reference is to a feature on most spacecraft named a Marmanflange but it will be understood the present capture mechanism isconfigured to capture any available feature on a spacecraft notnecessarily intended to be grasped. Referring to FIGS. 1A, 1B, 2, 3 and4, capture mechanism shown generally at 100 includes a capture mechanismhousing 1, a rigidisation mechanism housing 2, and a rigidisationmechanism mount 3. The capture mechanism 100 includes a single jaw 5 inopposition to a double jaw 6 which are shown in the open position. Tworigidisation brackets 7 are located in the vicinity of jaws 5 and 6 andprovide outer surfaces 70 against which a Marman bracket 39 abuts onceit has been captured. At the other end of the housing opposite jaws 5and 6 is located a capture mechanism mount 16. This mount is used toattach the capture mechanism to the end of a manipulator arm. Located infront of the rigidisation mechanism mount 3 are two capture mechanismreturn pins 19 located on opposite sides of the housing 1 from eachother. Associated with each of the return pins 19 is a capture mechanismreturn spring 20 located in housings below pins 19. At the front of thecapture mechanism housing 1 are two capture mechanism stop pins 18 eachone located in front of one of the pins 19. A mount 72 is located onrigidisation mechanism housing 2.

FIGS. 1A, 1B and 2 show the capture mechanism in the open and armedposition ready to capture a Marmam bracket 39, while FIGS. 3 and 4 showthe capture device 100 closed after capturing the Marman bracket 39.

Referring now to FIGS. 5 and 6, the capture mechanism 100 includes twomotor brackets 8, a motor 9 mounted to brackets 8, a gearbox 10 coupledwith motor 9, a collet 11 coupled to the gearbox 10, a rigidisationdrive shaft 12 coupled to collet 11, a rigidisation drive nut 13surrounding drive shaft 12, a rigidisation drive nut spacer 14 and arigidisation drive spacer retaining ring 15. Rigidisation drive shaft 12reciprocates back and forth in the rigidisation mechanism housing 2 andrigidisation drive nut 13, rigidisation drive nut spacer 14 and ring 15are located in the mechanism mount 16. The mechanism mount fasteners 17secure mechanism mount 16 to rigidisation mechanism housing 2.

Referring to FIGS. 7 and 8, details of the structure of the capturemechanism are shown. The capture mechanism includes:

-   two capture mechanism cams 21,-   two cam drive links 22-   plunger drive pin 23-   two cam drive link pivot pins 24-   two cam drive spring support pins 25-   two cam drive pins 26-   plunger draw bar 27-   two plunger draw bar bolts 28-   two plunger draw bar nuts 29-   rigidisation preload bushing 30-   rigidisation preload spring 31-   rigidisation preload washer 32-   rigidisation preload spring screw 33-   two capture mechanism frames 34-   two cam drive spring access plates 35-   two cam drive springs 36 (only visible in FIG. 9)-   two jaw hinge pins 37-   plunger reset stop ring 38

The two capture mechanism frames 34 serve to structurally contain andsupport the main components of the capture mechanism 100 and arefastened together as a unit prior to being inserted with the capturemechanism housing 1. Within the two frames 34 the two cam drive links 22are interleaved, and retained within a slot 103 (see FIGS. 8 and 9) inthe trigger plunger 4 by the plunger drive pin 23. The trigger plunger 4and cam drive links 22 sit within the frames 34 with the plunger 4 freeto reciprocate fore and aft and the two cam drive links 22 pivotingabout two cam drive link pivot pins 26 fixed within the frames 34. Theother ends of the two cam drive links 22 are connected by the cam drivepins 26 to the two capture mechanism cams 21. The capture mechanism camssit within guide slots 42 (FIG. 8) forming part of the surface of theframes 34. Slots in the cam drive links 22 permit the capture mechanismcams 21 to slide fore and aft as the cam drive links 22 rotate about thecam drive link pivot pins 26. A cam drive spring support pin 25 isinserted in each cam drive link 22 and these act to hold the two camdrive springs 36 (one being shown in FIG. 9). These tension springs 36act upon the cam drive links 22 and act in such a way to bring the camdrive support pins 25 closer together. This spring force creates amoment around the cam drive link pivot pins 26 to operate the mechanism.To provide access to the two cam drive springs 36 there are two camdrive spring access plates 35, one each for the top and bottom of themechanism.

The capture mechanism cams 21 are in contact at point 41 with the singlejaw 5 and double jaw 6 along a specifically devised follower surface 43on the two jaws. As the capture mechanism cams 21 move fore and aft theforces on the single and double jaws 5 and 6 cause them to rotate aroundthe jaw hinge pins 37 which hold the jaws 5 and 6 into the capturemechanism 100. The shape of the surface combined with the contact of thecapture mechanism cams 21 controls the opening and closing of the twojaws 5 and 6. Jaw motion speeds, the extent of closure and themechanical advantage of the jaw closing action is controlled by varyingthe interaction between the cam surface 41 and the jaw follower surfaces43.

The plunger draw bar 27 extends through slot 44 in the trigger plunger 4and is connected to the motor brackets 8 by a bolt 28 and nut 29 on eachside. Aft of the plunger draw bar 27 are, in order, the rigidisationpreload bushing 30, the rigidisation preload spring 31 and therigidisation preload washer 32 all fastened to the trigger plunger 4 bythe rigidisation preload spring screw 33. The rigidisation preloadbushing 30, the rigidisation preload spring 31, the rigidisation preloadwasher 32 and the rigidisation preload spring screw 33 serve to even outthe loads imposed by the plunger draw bar 27 on the trigger plunger 4during rigidisation, These parts also serve to compensate for anyvariations in component axial dimensions due to differential thermalgrowth should the temperature of the mechanism 100 change.

The plunger reset stop ring 38 is installed into a groove in the triggerplunger 4 in such a way that it acts as a final stop to the mechanismwhen it is being reset. When the plunger reset stop ring 38 contacts theaft face of the assembled capture mechanism frames 34 it provides asignal to a control system that the mechanism has been pushed forward asfar as it can go. The control system then commands the motor 9 to drivethe trigger plunger 4 aft a predetermined distance to create the correctoperating clearance in front of the plunger draw bar 27 within slot 44and the capture mechanism 100 is reset and ready to capture anotherfeature

Referring to FIGS. 9, 10 and 11 and given that the capture mechanismframes are free to reciprocate with the capture mechanism housing, thecapture mechanism return springs 20 acts upon the capture mechanismreturn pins 19 which are fastened to the two capture mechanism frames 34to bias the quick grasp mechanism in housing 1 into the forwardposition, aligned and ready for capture. These springs 20 ensure thatthe mechanism is operated in the correct sequence and that the capturemechanism frames remain in the correct axial position.

FIG. 15 is a block diagram showing those items pertaining to the captureof a client satellite in addition to the capture mechanism 100. Theseinclude the host servicer spacecraft 400, the client satellite 40 withbracket 39 to be captured, a robotic arm 403, an end effector 411coupled to the robotic arm 403, to which the capture mechanism 100 isinterfaced and releasibly gripped by the end effector 411, and acommunication system 410 to provide a two-way radio link 407 to Earth408 (or space station or mother ship-whichever is the location of theteleoperation control).

In addition, the servicer spacecraft 400 includes an onboard computercontrol system 500 (see FIG. 16) which may be interfaced with thecapture mechanism 100, so that it can coordinate all the components thatare involved in the capture process, including the vision system 550,robotic arm(s) 403 (if more than one capture mechanism 100 is used).This control system is also interfaced with any sensors used todetermine the position and loading state of the software capture orrigidize mechanisms. These sensors may include contact or non-contactsensors used to trigger the quick grasp mechanism (in lieu of theplunger) and position sensors to determine the degree of closure of themechanisms using continuous means (encoders or resolvers) or discretely(using limit switches). With the presence of the computer control system500 interfaced with the capture mechanism 100, the capture process maybe autonomously controlled by a local Mission Manager or may includesome levels of supervised autonomy so that in addition to being underpure teleoperation there may be mixed teleoperation/supervised autonomy.

Referring now to FIGS. 15 and 16, an example computing system 500forming part of the propellant resupply system is illustrated. Thesystem includes a computer control system 525 configured, and programmedto control movement of the robotic arm 403 during the entire procedureof capturing flange 39 on the client satellite 40.

The command and control system is also configured to control movement ofthe robotic arm 403 and the end effector 411 attached thereto forcontrolling the action of the capture mechanism 100. This may be thesame command and control system that is interfaced with the capturemechanism, for example a computer mounted on the servicer satellitewhich is programmed with instructions to carry out all operations neededto be performed by the servicer satellite during approach,capture/docking with the client satellite and refueling operations. Itmay also be a separate computer system.

Communication system 410 is interfaced with the robotic arm 403 andconfigured to allow remote operation (from the Earth 408 or from anyother suitable location) of the vision system 550 (which may include oneor more cameras), the robotic arm 403 and hence the tools. The visionsystem 550 may include distinct markers mounted on capture mechanism100.

In one form, the vision system 550 may include one or more videocameras. To improve depth perception, it may be augmented with a rangefinding device, such as a laser range finder or radar. The cameras ofvision system 550 may be used within a telerobotic control mode where anoperator controlling the servicing actions on earth or from some otherremote location views distinct views of the worksite on display screensat the command and control console. In an alternative mode, the positionof elements of the tool 100 or flange 39 may be determined by either astereo camera and vision system which extracts 3D points and determinesposition and orientation of mechanism 100 or other relevant features onthe flange 39, satellite 401 or capture mechanism 100 from which therobotic arm 403 can be driven to desired locations according the sensed6 degree-of-freedom coordinates. It should be noted that the termposition in the context of the positioning of the servicing spacecraftwith respect to the spacecraft to be captured includes the orientationof the object as well as the translation vector between the two objects,i.e. the overall relative pose of the capture feature on the clientspacecraft with respect to servicer spacecraft.

The stereo camera could also be replaced with a scanning or flash lidarsystem from which desired 6 degree-of-freedom coordinates could beobtained by taking measured 3-D point clouds and estimating the pose ofdesired objects based on stored CAD models of the desired features orshapes on the refueling worksite. For those applications where thespacecraft was designed with the intention to be serviced, a simpletarget such as described in Ogilvie et al. (Ogilvie, A., Justin Allport,Michael Hannah, John Lymer, “Autonomous Satellite Servicing Using theOrbital Express Demonstration Manipulator System,” Proc. of the 9thInternational Symposium on Artificial Intelligence, Robotics andAutomation in Space (i-SAIRAS '08), Los Angeles, Calif., Feb. 25-29,2008) could be used in combination with a monocular camera on theservicing robotics to locations items of interest. Finally, the roboticarm or device used to position the capture mechanism 100 may include asensor or sensors capable of measuring reaction forces between thecapture tool and the bracket being captured. These can be displayed tothe operator to aid the operator in tele-operation control or can beused in an automatic force-moment accommodation control mode, whicheither aids a tele-operator or can be used in a supervised autonomouscontrol mode.

As mentioned above, computer control system 525 is interfaced withvision system 550 and robotic arm 403. Previously mentionedcommunication system 410 is provided which is interfaced with therobotic arm 403 and configured to allow remote operation (from the Earth408 or from any other suitable location) of the vision system 550 (therobotic arm 403, robotic end effector 411, and capture mechanism 100. Asystem of this type is very advantageous particularly for space basedsystems needing remote control.

The end effector 411 possesses its own embedded processor (as does therobotic arm 403) and receives commands from the servicing spacecraftcomputer. The end effector 411 also passes power and data from thecentral computer through to the capture mechanism 100 in the event thereare sensors of any type, gauges or other power requiring devices.

Some aspects of the present disclosure can be embodied, at least inpart, in software. That is, the techniques can be carried out in acomputer system or other data processing system in response to itsprocessor, such as a microprocessor, executing sequences of instructionscontained in a memory, such as ROM, volatile RAM, non-volatile memory,cache, magnetic and optical disks, or a remote storage device. Further,the instructions can be downloaded into a computing device over a datanetwork in a form of compiled and linked version. Alternatively, thelogic to perform the processes as discussed above could be implementedin additional computer and/or machine readable media, such as discretehardware components as large-scale integrated circuits (LSI's),application-specific integrated circuits (ASIC's), or firmware such aselectrically erasable programmable read-only memory (EEPROM's).

FIG. 16 provides an exemplary, non-limiting implementation of computercontrol system 525, forming part of the command and control system,which includes one or more processors 530 (for example, aCPU/microprocessor), bus 502, memory 535, which may include randomaccess memory (RAM) and/or read only memory (ROM), one or more internalstorage devices 540 (e.g. a hard disk drive, compact disk drive orinternal flash memory), a power supply 545, one more communicationsinterfaces 410, and various input/output devices and/or interfaces 555.

Although only one of each component is illustrated in FIG. 18, anynumber of each component can be included computer control system 525.For example, a computer typically contains a number of different datastorage media. Furthermore, although bus 502 is depicted as a singleconnection between all of the components, it will be appreciated thatthe bus 502 may represent one or more circuits, devices or communicationchannels which link two or more of the components. For example, inpersonal computers, bus 502 often includes or is a motherboard.

In one embodiment, computer control system 525 may be, or include, ageneral purpose computer or any other hardware equivalents configuredfor operation in space. Computer control system 525 may also beimplemented as one or more physical devices that are coupled toprocessor 530 through one of more communications channels or interfaces.For example, computer control system 525 can be implemented usingapplication specific integrated circuits (ASIC). Alternatively, computercontrol system 525 can be implemented as a combination of hardware andsoftware, where the software is loaded into the processor from thememory or over a network connection.

Computer control system 525 may be programmed with a set of instructionswhich when executed in the processor causes the system to perform one ormore methods described in the present disclosure. Computer controlsystem 525 may include many more or less components than those shown.

While some embodiments have been described in the context of fullyfunctioning computers and computer systems, those skilled in the artwill appreciate that various embodiments are capable of beingdistributed as a program product in a variety of forms and are capableof being applied regardless of the particular type of machine orcomputer readable media used to actually effect the distribution.

A computer readable medium can be used to store software and data whichwhen executed by a data processing system causes the system to performvarious methods. The executable software and data can be stored invarious places including for example ROM, volatile RAM, non-volatilememory and/or cache. Portions of this software and/or data can be storedin any one of these storage devices. In general, a machine readablemedium includes any mechanism that provides (i.e., stores and/ortransmits) information in a form accessible by a machine (e.g., acomputer, network device, personal digital assistant, manufacturingtool, any device with a set of one or more processors, etc.). Examplesof computer-readable media include but are not limited to recordable andnon-recordable type media such as volatile and non-volatile memorydevices, read only memory (ROM), random access memory (RAM), flashmemory devices, floppy and other removable disks, magnetic disk storagemedia, optical storage media (e.g., compact discs (CDs), digitalversatile disks (DVDs), etc.), among others. The instructions can beembodied in digital and analog communication links for electrical,optical, acoustical or other forms of propagated signals, such ascarrier waves, infrared signals, digital signals, and the like.

The present system is also configured for full autonomous operation. Afully autonomous system is a system that measures and responds to itsexternal environment; full autonomy is often pursued under conditionsthat require very responsive changes in system state to externalconditions or for conditions that require rapid decision making forcontrolling hazardous situations. The implementation of full autonomy isoften costly and is often unable to handle unforeseen or highlyuncertain environments. Supervised autonomy, with human operators ableto initiate autonomous states in a system, provides the benefits of aresponsive autonomous local controller, with the flexibility provided byhuman teleoperators.

The operation of the capture mechanism will now be described withreference to the feature on the spacecraft being captured as being aMarman flange 39 (but any other suitable feature could be grasped aswell). The mechanism 100 will be manoeuvred into position above thetarget Marman flange 39 by a manipulator arm (not shown) of suitableconfiguration or even by manoeuvering a spacecraft to which themechanism 100 is directly attached. The arm or spacecraft will be guidedby signals returned from a vision system attached to or near the capturemechanism in response to human commands given from the ground, from aspacecraft attached to the arm, autonomously via a computer controlsystem connected to the arm or spacecraft or a combination of both humanand computer control.

When the control system has determined that the target flange 39 iswithin the capture envelope, the arm or spacecraft is commanded to movethe mechanism forward until the mechanism is triggered. The mechanismmay be triggered electronically via a contact or noncontact sensor ormechanically. In this embodiment, the mechanism is triggeredmechanically.

FIGS. 1 and 3 show the mechanism in the armed configuration. Themechanism is in the “armed” or “ready to capture” position when thecapture mechanism cams 21 are held in the aft position by two cam drivesprings 36 (also seen only in FIG. 9) which are attached to the two camdrive links 22 (seen only in FIG. 9). These springs keep the triggerplunger 4 pushed forward and keep the capture mechanism cams 21 pulledback within the tool. This forces the two jaws 5 and 6 to the openposition. The mechanism is triggered when the trigger plunger 4 isforced back within the tool by the contact forces that occur when themechanism is forced into the target flange 39 as shown in FIG. 5. As thetrigger plunger 4 moves aft within the mechanism, the attached plungerdrive pin 23 (shown in FIG. 7) forces the two cam drive links 22 torotate about the cam drive link pivot pins 24. This motion is resistedby the cam drive springs 36 until a point where the cam drive links 22go over centre. At that point the cam drive springs 36 try to pull thecam drive spring support pins 25 closer together causing the cam drivelinks 22 to rotate around the cam drive link pivot pins 24.

As the cam drive links 22 rotate they push the capture mechanism cams 21forwards within the cam slots 42. The cam follower surfaces 41 on thecapture mechanism cams push on the cam contact surface 43 on the singleand double jaws 5 and 6 and this forces the jaws together, trapping thetarget flange 39. At the same time the trigger plunger is forced aft bythe cam drive springs. Sensors can be positioned within mechanism bodyto sense when the trigger plunger 4 has moved to provide an indicationto the control system that the mechanism has been triggered. A slot 44in the trigger plunger permits the plunger to move around the fixedplunger draw bar 27.

FIG. 2 shows the mechanism in the closed, but not rigidisedconfiguration. The target flange is considered “soft captured”. Aftersoft capture has been achieved the mechanism has to be rigidised toachieve the full structural interface with the target spacecraft 40. Inthis embodiment, the actuator that rigidises the mechanism is a motorcontained within the tool but that actuator could be any other type ofmechanical actuation, be it springs, gas generator, paraffin actuator,solenoid or even a motor in a remote location connected by a powertrainof some sort.

To rigidise the mechanism after soft capture the control system commandsthe motor 9 to turn which, via the gearbox 10 and collet 11 turns therigidisation drive shaft 12. The rigidisation drive shaft 12 turnswithin the rigidisation drive nut 13 which then draws the motor 9 andits motor brackets 8 further aft into the rigidisation mechanism housing3. The rigidisation mechanism housing 3 is connected to the plunger drawbar 27 and pulls the draw bar back with it as it moves. The plunger drawbar 27 moves within slot 44 in the trigger plunger 4. The motor 9 pullsthe draw bar aft until it contacts the rigidisation preload bushing 30which is connected through the rigidisation preload spring 31,rigidisation preload washer 32 and rigidisation preload spring screw 33to the trigger plunger 4. The rigidisation preload spring ensures thatexcessive tensile forces are not imposed on the rigidisation components.

The two, connected capture mechanism frames 34 are free to move withinthe capture mechanism housing 1. As the trigger plunger is pulled aft bythe motor it applies more torque to the two cam drive links 22 forcingthe capture mechanism cams 21 even further forwards which grasps theMarman flange 39 even more securely and centres it within the jaws. Oncethe cams are as far forward as possible (limited by the flexibility ofthe jaws, the wedge angle that the closed jaws make and the forwardforce on the cams) the rigidisation actuator starts to pull the entirecapture mechanism (jaws, frames and cams) and the captured Marman flange39 aft via the trigger plunger 4. The motor continues to pull the Marmanflange aft until the surface of the Marman flange contacts the frontface of the two rigidisation brackets 7. Once contact has been made, themotor 9 continues to pull the quick grasp mechanism in housing 1 aftuntil the control system senses, in this case, via current sensing andcounting the number of drive shaft turns, that the Marman flange 39 hasbeen drawn against the rigidisation brackets 7 with the specified amountof force. The mechanism is now considered fully rigidised with theMarman bracket 39 and spacecraft 40 rigidised against the brackets 7.

To reset the mechanism, the motor 9 is reversed and the draw bar 27moves forwards in slot 44 until it contacts the front of the slot andstarts to push the trigger plunger forwards. As the load is removed fromthe capture mechanism frames 34 the two capture mechanism return springs20 move the entire quick grasp mechanism in housing 1 forward and theMarman flange 39 is moved off of the rigidisation brackets 7, yet isstill captured by the jaws 5 and 6 in their fully closed position. Thequick grasp mechanism contained in housing 1 continues to move forwarduntil the capture mechanism frames 34 come in contact with the capturemechanism stop pins 18 which inhibit further forward movement of thequick grasp mechanism. The motor 9 continues to drive the triggerplunger 4 forward and this causes the plunger drive pin 23 to cause thecam drive links 22 to rotate and pull the two capture mechanism cams 21aft. As the capture mechanism cams 21 move aft, first the load on theMarman flange 39 reduces and, towards the very end of cam travel, theshape of the cam follower surfaces 43 causes the jaws to open andmechanism is completely disengaged from the Marman flange 39. With thecapture mechanism frames 34 fully forward, the motor 9 continues todrive the trigger plunger 4 forward until the plunger reset stop ring 38contacts the aft face of the capture mechanism frames 34. At this pointthe cam drive links have moved back over centre and are cocked and readyto be activated again. The increase in motor current as the motor stallsindicates to the control system that the mechanism is at the resetpoint. The motor is stopped and then commanded to pull the triggerplunger aft a predetermined amount to a point where, when the plunger istriggered and quickly moves aft slot 44 will not hit the front face ofthe draw bar 27. The mechanism is now completely reset and ready tocapture another target flange.

Thus, the present spacecraft capture mechanism is for capturing a railand or flange feature on a free flying spacecraft. The mechanismincludes a capture mechanism including a two stage grasping tool. Thegrasping tool includes a quick grasp mechanism mounted for movement inhousing 1, which is configured to clamp the feature when the feature isin close proximity to, and triggers the quick gasp mechanism to softcapture the feature (shown as Marman flange 39 in the figures). Thequick grasp mechanism includes jaws 5 and 6, and associated cammechanism located in housing 1. The capture mechanism includes arigidizing mechanism located in housing 2 configured to draw the quickgrasp mechanism and soft captured feature into housing 1 till thefeature abuts against a rigidisation surface located in the firsthousing to rigidize the feature and spacecraft against housing 1. Asshown in FIGS. 1 to 8 the rigidizing mechanism includes a pullingmechanism connected to the elongate plunger 4 configured to draw theelongate plunger 4 and the clamping jaws 5 and 6 further into the firsthousing section 1, the first housing section 1 and the cam mechanismbeing configured so that as the clamping jaws 5 and 6 are withdrawn intothe first housing section 1 the cam portions engaging the clamping jaws5 and 6 are biased closer together. The pulling mechanism is configuredto further pull the clamping mechanism into the first housing 1 until aportion of the bracket abuts up against rigidisation brackets 7 tothereby rigidiize the captured spacecraft to the capture mechanism.

A non-limiting embodiment of the pulling mechanism includes motor 9,gear box 10 and collet 11. The motor 9 is coupled to the trigger plunger4 by the motor brackets 8 which are coupled through the plunger draw bar27 to trigger plunger 4 and to the rigidisation mechanism housing 2through the rigidisation drive shaft 12 and the rigidisation drive nut13.

Quicker-Acting Capture Mechanism

A further embodiment increases the capture speed of the device by addingan additional mechanism. This third mechanism holds the capturemechanism illustrated in FIG. 1 and couples it with a spring and, ifrequired by spacecraft dynamics consideration, also couples it to arecoil mass to limit the reaction forces on the host spacecraft when themechanism activates. The device is comprised of the following componentsshown in FIGS. 12, 13 and 14:

-   45. capture mechanism assembly similar to that shown in FIG. 1.-   46. main housing-   47. linear bearing (qty 2 req'd)-   48. capture mechanism support carriage-   49. reset actuator-   50. reset cable spool (qty 2 req'd)-   51. reset cable (qty 2 req'd)-   52. reset cable idler (qty 2 req'd)-   53. recoil mass-   54. recoil damper-   55. reciprocation spring-   56. recoil mass support carriage-   57. recoil mass release arm-   58. mechanism release actuator-   59. capture mechanism release arm

FIG. 12 shows the device armed and ready to be activated. Similar to theprevious embodiment, this version must be placed in a position where thetarget spacecraft 40 and its Marman flange 39 are within the mechanism'scapture envelope by an arm or by the host spacecraft's control system.Again, this can be accomplished via direct ground control, on boardautonomous computer control or by an advantageous combination of thetwo. Once the target Marman flange is within the envelope of the devicethe control system commands the mechanism release actuator 58 tosimultaneously release the capture mechanism assembly 45 and the recoilmass 53. The capture mechanism is pushed forward a prescribed distanceand the Recoil Mass is pushed backwards at the same time. The capturemechanism assembly is supported by the capture mechanism supportcarriage 48 and the recoil mass is supported by the recoil mass supportcarriage 56. Both support carriages run on a set of aligned linearbearings 47 that guide the axial movement of the two sub-assemblies andconnect the support carriages to the main housing 46.

As the capture mechanism assembly reaches approximately the end of itstravel, and if the computations regarding the future position of thetarget flange were correct when the device was triggered, then triggerplunger 4 on the capture mechanism assembly will strike the surface ofthe target flange and initiate the capture sequence outlined above. Atthe same time, the recoil mass has hit the end of its travel and toprovide a final protection against impact shock (which can be harmful todelicate spacecraft components) comes into contact with the recoildamper 54 which absorbs almost all of any remaining deceleration forcesand brings the recoil mass to a stop. A series of one-way brakes in therecoil mass support carriage help prevent the recoil mass fromrebounding back down the linear bearings in an uncontrolled manner.These brakes can be of the limited slip type which would permit therecoil mass to slowly move back towards the reset position or they canbe rigid brakes permitting the actions of the various elements to becontrolled individually. As similar set of brakes on the capturemechanism support carriage prevent its uncontrolled rebound when itreaches the end of its travel. If required to limit capture mechanismassembly deceleration shocks a damper similar to the recoil damper canbe placed in the path of the capture mechanism assembly.

With the target flange captured in the jaws of the capture mechanismassembly, the capture mechanism support carriage is locked to the linearbearings and the capture mechanism assembly rigidises its grasp of thetarget flange as described for the basic mechanism, above. Once thetarget is held rigidly in the grasp of the mechanism the capturemechanism assembly may be pulled back into the device. Resetting thedevice is accomplished by engaging the reset actuator 49, which, in thiscase is a motor gearbox but could as well be a clockwork, a shape memoryalloy actuator, a paraffin actuator or any number of other acceptableactuators that serve to draw the capture mechanism assembly and therecoil mass back towards their initial position. In this case the resetactuator turns two reset cable spools 50 which draw in the two resetcables 51 that are attached to the two support carriages. Once thecapture mechanism support carriage and the recoil mass support carriagereach the point where the reciprocation spring has achieved the correctamount of compression necessary to activate the device for the nextcapture attempt, the two support carriages are locked into the linearbearings and the capture mechanism release arms 59 re-engage connectingthe mechanism release actuator to the two support carriages.

As a last step, the rotation of the reset spools 50 is uncoupled fromthe reset actuator 49 by means of a clutch or released brake (not shown)so that the reset spools may quickly pay out cable the next time thatcapture is initiated. The capture mechanism is now reset and ready tomake another capture operation. The jaws of the capture mechanism can beopened independently of the capture action so that the target satellitecan be released without initiating the reciprocating action.

There may be operational considerations that require that the targetsatellite be held without rigidising while the capture mechanismassembly and this sequence of events can be supported by the device bysimply changing the sequence in which the actuators are commanded.Similarly, by leaving the reset actuator coupled to the reset spools itcan be used to slowly pay out the capture mechanism assembly as opposedto the rapid capture action, should that prove advantageous.

By controlling the various masses and any braking or drag forces beingapplied by the two support carriages to motion down the linear bearings,the speeds and accelerations of the mechanism can be fine-tuned. Ifactuators are included in the support carriages, this fine-tuning cantake place during the capture event permitting a significant level ofcontrol over the capture event.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

Therefore what is claimed is:
 1. A system for capturing a feature on afree flying spacecraft, comprising a capture mechanism including a twostage grasping tool including i) a quick grasp mechanism having clampingjaws configured to be sprung closed, said quick grasp mechanism beingmounted for movement in a housing, said quick grasp mechanism configuredto clamp said feature when said feature is in close proximity to, andtriggers said clamping jaws to be sprung quickly and sufficiently shutsuch that the feature cannot escape from said clamping jaws thusachieving soft capture of the feature; and ii) a rigidizing mechanism,independently actuated from said quick grasp mechanism and configuredto, upon completion of the soft capture of the feature, draw the quickgrasp mechanism and the soft captured feature into said housing untilsaid soft captured feature abuts against a rigidisation surface locatedin said housing to rigidize the soft captured feature and spacecraftrelative to said housing.
 2. The system according to claim 1, furthercomprising a) a positioning mechanism releasibly attachable to thecapture mechanism capable of positioning the capture mechanism intoclose proximity to the feature to trigger the quick grasp mechanism; andb) a sensing system for ascertaining a relative position of the capturemechanism and the feature.
 3. The system according to claim 1 includinga computer control system connected to said sensing system and saidpositioning mechanism and programmed to position the capture mechanismin close proximity to said feature to trigger said quick graspmechanism.
 4. The system according to claim 3 wherein said computercontrol system is further programmed to control the actions of saidquick grasp and ridigizing mechanisms.
 5. The system according to claim3 including a second computer control system programmed to control theactions of said quick grasp and ridigizing mechanisms.
 6. The systemaccording to claim 3 further comprising a communication systemconfigured to provide communication between a command and control systemand a remote operator for remote teleoperator control, supervisedautonomous control, or fully autonomous control of fluid transferoperations between the servicer spacecraft and the client satellite. 7.The system according to claim 6 wherein said sensing system includes avision system mounted and configured to provide real time images of allcapture and release operations, said vision system being connected tosaid communication system for transmitting said images to a teleoperatorduring teleoperation.
 8. The system according to claim 6 wherein saidsensing system includes a vision system mounted and configured toprovide real time images of all fluid transfer operations, said visionsystem being connected to said communication system for transmittingsaid images and being configured to be used in an autonomous controlsystem.
 9. The system according to claim 1 wherein said capturemechanism includes a first housing section in which said quick graspmechanism is mounted, said clamping jaws having proximal sectionspivotally mounted to a front portion of said first housing section andextending outwardly from a front of said first housing section, abiasing mechanism located in said first housing section configured forbiasing distal sections of the clamping jaws apart, the biasingmechanism including an elongate plunger mounted for reciprocal movementalong an axis of the first housing section, the biasing mechanismincluding a cam mechanism pivotally mounted to said elongate plunger andconfigured to have a cam portion engage said clamping jaws to bias thedistal sections of the clamping jaws apart when the elongate plunger isfully extended forward of the first housing section, the cam mechanismbeing configured so that when the elongate plunger contacts a bracketmounted to a spacecraft and is moved inwardly into said first housingsection the cam mechanism pivots with respect to said elongate plungercausing the cam portions engaging said clamping jaws to move forwardforcing the distal ends of the clamping jaws to pivot toward each otherthereby capturing a portion of the bracket; and said rigidisationmechanism being mounted in a second housing section, said second housingsection mounted to a back of said first housing section, saidrigidisation mechanism including a pulling mechanism connected to theelongate plunger configured to draw the elongate plunger and theclamping jaws further into the first housing section, the first housingsection and cam mechanism being configured so that as the clamping jawsare withdrawn into the first housing section the cam portions engagingsaid clamping jaws are biased closer together, the pulling mechanismbeing configured to further pull the clamping mechanism into said firsthousing until a portion of the bracket abuts up against a rigidisationbracket to thereby rigidiize the captured spacecraft to the capturemechanism.
 10. A capture mechanism for capturing a bracket mounted to aspacecraft, comprising: a) a first housing section, a quick graspmechanism mounted in said first housing section, said quick graspmechanism including clamping jaws having proximal sections pivotallymounted to a front portion of said first housing section and extendingoutwardly from a front of said first housing section, a biasingmechanism located in said first housing section configured for biasingdistal sections of the clamping jaws apart, the biasing mechanismincluding an elongate plunger mounted for reciprocal movement along anaxis of the first housing section, the biasing mechanism including a cammechanism pivotally mounted to said elongate plunger and configured tohave a cam portion engage said clamping jaws to bias the distal sectionsof the clamping jaws apart when the elongate plunger is fully extendedforward of the first housing section, the cam mechanism being configuredso that when the elongate plunger contacts a bracket mounted to aspacecraft and is moved inwardly into said first housing section the cammechanism pivots with respect to said elongate plunger causing the camportions engaging said clamping jaws to move forward forcing the distalends of the clamping jaws to pivot toward each other thereby capturing aportion of the bracket; and b) a second housing section mounted to aback of said first housing section, a rigidisation mechanism mounted insaid second housing section, said rigidisation mechanism including apulling mechanism connected to the elongate plunger configured to drawthe elongate plunger and the clamping jaws further into the firsthousing section, the first housing section and cam mechanism beingconfigured so that as the clamping jaws are withdrawn into the firsthousing section the cam portions engaging said clamping jaws are biasedcloser together, the pulling mechanism being configured to further pullthe clamping mechanism into said first housing until a portion of thebracket abuts up against a rigidisation bracket to thereby rigidiize thecaptured spacecraft to the capture mechanism.